From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22140 invoked by alias); 15 Feb 2011 21:38:29 -0000 Received: (qmail 22132 invoked by uid 22791); 15 Feb 2011 21:38:28 -0000 X-SWARE-Spam-Status: No, hits=-3.1 required=5.0 tests=AWL,BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,RCVD_IN_DNSWL_LOW,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from smtp-out.google.com (HELO smtp-out.google.com) (74.125.121.67) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 15 Feb 2011 21:38:23 +0000 Received: from kpbe14.cbf.corp.google.com (kpbe14.cbf.corp.google.com [172.25.105.78]) by smtp-out.google.com with ESMTP id p1FLcKud019006 for ; Tue, 15 Feb 2011 13:38:20 -0800 Received: from yib17 (yib17.prod.google.com [10.243.65.81]) by kpbe14.cbf.corp.google.com with ESMTP id p1FLcI2Z018395 (version=TLSv1/SSLv3 cipher=RC4-SHA bits=128 verify=NOT) for ; Tue, 15 Feb 2011 13:38:19 -0800 Received: by yib17 with SMTP id 17so347595yib.35 for ; Tue, 15 Feb 2011 13:38:18 -0800 (PST) Received: by 10.236.108.43 with SMTP id p31mr4455741yhg.69.1297805898186; Tue, 15 Feb 2011 13:38:18 -0800 (PST) Received: from coign.google.com (dhcp-172-22-125-221.mtv.corp.google.com [172.22.125.221]) by mx.google.com with ESMTPS id 66sm2635622yhl.46.2011.02.15.13.38.17 (version=TLSv1/SSLv3 cipher=OTHER); Tue, 15 Feb 2011 13:38:17 -0800 (PST) From: Ian Lance Taylor To: kevin diggs Cc: gcc-help@gcc.gnu.org Subject: Re: code gen for C string literals References: Date: Tue, 15 Feb 2011 23:11:00 -0000 In-Reply-To: (kevin diggs's message of "Tue, 15 Feb 2011 13:42:04 -0600") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-System-Of-Record: true X-IsSubscribed: yes Mailing-List: contact gcc-help-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: Sender: gcc-help-owner@gcc.gnu.org X-SW-Source: 2011-02/txt/msg00222.txt.bz2 kevin diggs writes: > On Tue, Feb 15, 2011 at 11:25 AM, Ian Lance Taylor wrot= e: >> kevin diggs writes: >> >> >> GIMPLE is the representation used by the middle-end. > > ??? what is the relationship between GIMPLE and RTL, which at my VERY > EARLY understanding of what goes on under the hood I would have > thought was the middle-end representation? Is RTL "the back-end > representation" (my guess would have been asm though maybe that is the > output)? Yes, RTL is also a representation used by the middle-end. RTL is much more machine specific than GIMPLE. The middle-end starts with the conversion to GIMPLE. It runs a bunch of general optimization passes. Then the GIMPLE is converted to RTL. Then comes a few more optimization passes, then stuff like register allocation, instruction scheduling, and final code generation. >> SSA is a compiler optimization technique which heavily influences the >> design of the intermediate representation. =C2=A0See >> http://en.wikipedia.org/wiki/Static_single_assignment_form . >> > Is SSA new? i.e. in what gcc version did it start getting used? SSA was introduced into gcc in version 4.0. Ian